In an internal combustion engine, it is known for a fuel pump to supply fuel at high pressure for delivery to each cylinder of the engine by means of a dedicated fuel injector. In a known arrangement, the fuel injector is received within a bore provided in a cylinder head of the cylinder (the “injector pocket”), and a high pressure (HP) fuel pipe (or fuel supply line) is used to provide a fluid connection between the fuel injector and the fuel pump or accumulator volume/common rail. Two such arrangements are known in the art: in a first arrangement (e.g. FIG. 1) the end of the HP fuel pipe that connects with the fuel injector is received within a bore extending through the cylinder head and connecting with the injector pocket; while in a second arrangement (e.g. FIG. 4) the HP fuel pipe is mounted over the cylinder head and connects with the injector at a point above the injector pocket.